This section provides background information related to the present disclosure which is not necessarily prior art. In motor vehicles, due to increasing numbers of technical components and increasing requirements with regard to comfort, optimization is necessary in terms of both the structural volume and the functionality of the components. For example, large-displacement components for conditioning air, such as are known in stationary air conditioning systems in the form of combining chambers, flow channeling, and swirling apparatus, cannot be used in motor vehicles due to the limited space conditions. Moreover, it is desirable to reduce the number of components in air conditioning systems while at the same time increasing their efficiency.
Air conditioning systems of the prior art have air intake housings comprising an air intake for the outside air taken in from outside the passenger area of the vehicle, also referred to as fresh air, and an air intake for the recirculated air taken from inside the passenger area. The air is drawn by an air blower, via the intakes, into the air conditioning system, where it is conditioned and then conducted through suitable distribution openings into the passenger area.
The setting of a valve arranged inside the air intake housing determines whether the air that is drawn in consists of solely outside air, solely recirculated air, or a mixture of outside air and recirculated air. In most cases, the valve is mounted inside the housing so as to pivot between two end positions. The air flow that is drawn in can be combined by placing the valve in an intermediate position between the two end positions.
In air intake housings known in the prior art, when the valve is in intermediate positions between the air intake for outside air and the air intake for recirculated air, undesirable bypass mass flows are generated, in which outside air flows around the valve and is introduced, without conditioning, into the passenger area of the vehicle through the air intake for recirculated air. Such bypass mass flows allow outside air that is too cold or too warm, for example, to enter directly into the passenger area.
In the prior art, such undesirable bypass mass flows are countered by a housing comprising two valves, which are designed for blocking and opening up the air intake for outside air and the air intake for recirculated air.
However, the use of two valves increases the amount of installation space that is required and necessitates additional expenditures on control for coordinating the movement of the valves.
For example, DE 199 15 966 A1 discloses an air intake housing for a heating and/or air conditioning system of a motor vehicle. The air intake housing comprises an intake for outside air, an intake for recirculated air, an outlet connected to a fan, and a valve. The valve is mounted inside the housing so as to pivot between an outside air position and a recirculated air position, and can occupy intermediate positions. The air intake housing further comprises internal fins, which serve to channel the mass flow of outside air and the mass flow of recirculated air to the outlet of the housing. A direct passage of air from the outside air intake to the recirculated air intake is thereby prevented.
To achieve a consistent back pressure of the fresh air in the air intake duct at high vehicle speeds, and to counteract the air pressure in the passenger area, back pressure valves are installed in the region of the air intake since adjusting the speed of the blower to the vehicle speed is not sufficient for controlling the back pressure of the outside air, which is dependent on the vehicle speed. The back pressure valves therefore serve the purpose of back pressure compensation.
In the prior art, separate fresh air and recirculated air valves are provided, which are actuated via separate transmissions and/or supplementary servo motors.
Therefore, with conventional air intake housings having a single valve, which enables the settings “outside air” and “recirculated air” or “partially recirculated air” as intermediate settings, an additional, second valve is required for backpressure compensation. This is true particularly if in the “partially recirculated air” setting, part of the air is drawn in from the passenger area.
With backpressure compensation, the cross-section of the air intake is decreased based upon the vehicle speed, thereby decreasing the size of the air intake duct. Therefore, backpressure compensation is understood as a restriction of the high upstream pressure in the intake area of the air intake housing, which is generated by high vehicle speed.
DE 10 2006 012 604 A1 describes an air valve having a valve body in a vehicle air conditioning system. The valve body is composed of a valve framework and a molded foam piece attached thereto. The valve framework is adapted to the geometry of the closed cross-section of the air duct, and the molded foam body is adapted to the geometry of the air intake of the blower, and optionally to the opening geometry of the air duct to which it is assigned.
If the air valve is embodied as a backpressure valve, it will act both on the fresh air duct and on the recirculated air duct of the air conditioning system. The back pressure valve, which can be pivoted in front of the free flow area of the fresh air duct, restricts the flow of air passing through the opened fresh air duct and compensates for the back pressure generated at high vehicle speeds. Also provided is an additional cylinder valve, which surrounds the air valve with the same pivoting axis and serves as a fresh air/recirculated air valve.
However, it is desirable to avoid the use of two valves, for example, due to the excessive space requirement and high control costs associated therewith. Air conditioning systems comprising multiple valves are substantially more expensive and also require higher driving forces than air conditioning systems that comprise only one valve.
DE 10 2004 004 165 B3 discloses an air intake for a ventilation, heating or air conditioning system of a motor vehicle, comprising an outside air duct for supplying outside air, a recirculated air duct for supplying recirculated air, a pressurized air valve for controlling the outside air duct and a recirculated air valve for controlling the recirculated air duct. The recirculated air valve and the pressurized air valve are embodied as a combined ventilation valve, which enables a restriction of the mass air flow flowing through the outside air duct when the recirculated air duct is closed.
All the systems known in the prior art comprise additional elements at great instrumental expense, which also require additional space and a control system, resulting in higher costs, additional installation expenditure and corresponding maintenance requirements.
In addition, the valve geometries known in the prior art produce strong flow noises. By separating the flow and with swirling currents, the valves are excited to oscillation and vibration.